(1) Field of the Invention
The present invention relates to an electrophotographic process using an organic photoconductive photosensitive layer. More particularly, the present invention relates to an electrophotographic process in which the surface potential is always stable and hence images are stably formed.
(2) Description of the Prior Art
In a commercial electrophotographic copying machine, there is adopted a system in which at the start of the copying operation, electricity removal and cleaning of a photosensitive layer are first performed and operations of main charging, light exposure, development with a toner, transfer, electricity removal and cleaning are repeated a necessary number of times. Since the operations of electricity removal and cleaning are performed at the start of the copying operation to prevent poor copying resulting from contamination of the photosensitive layer during stoppage of the copying machine and the operations of electricity removal and cleaning again are performed at the termination of the copying operation, if an organic photoconductive photosensitive layer is used as a photosensitive material in an electrophotographic copying machine of this type, a certain disadvantage occurs. More specifically, there is observed a tendency that the image density of a print obtained in the first copying cycle is lower than that of a print obtained in the second or subsequent copying cycles. The reason for this undesirable phenomenon has not been clearly determined, but it is presumed that the reason will probably be that in the case of an organic photoconductive photosensitive layer, there is formed a carrier having a longer life than in the case of an inorganic photoconductive photosensitive layer, and since charging for removal of electricity is further performed on a photosensitive layer where removal of electricity has already been performed at the termination of the copying operation, influences of this charging for removal of electricity become prominent.